The hydroboration reaction, discovered by the author and his students, made organoboranes readily available. Recent developments have extended the applicability to the synthesis of cyclic, polycyclic, and various partially alklated organoboranes. Hydroboration exhibits remarkable regio- and stereoselectivity, while tolerating many functional groups. Accordingly, it is now possible to synthesize functional organoboranes of defined regio- and stereochemistry. Our recent studies of the chemistry of organoboranes have revealed their remarkable potentiality as synthetic intermediates. For exampel, several methods have been developed for the transfer of alkyl groups from boron to other compounds. In addition, three general methods have been found to replace boron with carbon, allowing use of the boron derivative as a template in the stereospecific syntheses of complex materials of biological importance. Other organoboranes are of interest as selectve reducing agents and blocking groups in the synthesis of carbohydrates, proteins, and other natural products. It is proposed to continue a study with the following objectives: 1) explore the stereospecific hydroboration of representative unsaturated molecules; 2) explore the selective and stereospecific reduction of functional groups; 3) explore the chemistry of such organoboranes as should be useful derivatives for medicinal and biochemical research; 4) develop practical conversions of organoboranes into other derivatives allowing the synthesis of complex materials of biological and pharmaceutical importance.